Comment 1 for bug 305687

If someone gets to this before me, one thing to keep in mind is that upgrading the invirt-vnc-{client,server} binary packages won't cause the newly stale source package to vanish from the apt repo.

You'll want to run:
reprepro-env -T dsc remove stable invirt-vnc-server

(loop over all combinations of {stable,unstable} and {server,client})